Table 2.

Assessing the quality of non-randomized studies by Newcastle-Ottawa Scale

	Selection	Comparability	Outcome	Overall quality
Bhasin 2012 [25]	★★	★	★★★	Moderate
Bhasin 2013 [26]	★★	★	★★★	Moderate
Bhasin 2016 [27]	★★	★★	★★	Moderate
Bhasin 2017 [28]	★★	★	★★★	Moderate
Ghali 2016 [29]	★★	★★	★★★	High
Meng 2009 [30]	★★	★	★★★	Moderate
Moniche 2012 [31]	★★	★★	★★★	High